/*
 * Copyright (C) 2021 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.tumblr.backboard.Utils;

/**
 * A property is an abstraction that can be used to represent value that is held in object. The Property's methods
 * can be implemented in terms of the private fields of the host object, or via "setter" and "getter" methods or by
 * some other mechanism, as appropriate.
 *
 * @author stt
 * @param <T> The class on which the property is declared.
 * @param <V> The type that this property represents.
 * @since 2021-05-07
 */
public abstract class Property<T, V> {
    private final String mName;
    private final Class<V> mType;

    /**
     * A constructor that takes an identifying name and { #getType() type} for the property.
     *
     * @param type type
     * @param name name
     */
    public Property(Class<V> type, String name) {
        mName = name;
        mType = type;
    }

    /**
     * This factory method creates and returns an Property given the <code>class</code> and parameters, where the
     * <code>"name"</code> parameter represents either:
     * <ul>
     * <li>a public <code>getName()</code> method on the class which takes no arguments, plus an
     * optional public <code>setName()</code> method which takes an value of the same type
     * returned by <code>getName()</code>
     * <li>a public <code>isName()</code> method on the class which takes no arguments, plus an
     * optional public <code>setName()</code> method which takes an value of the same type
     * returned by <code>isName()</code>
     * <li>a public <code>name</code> field on the class
     * </ul>
     *
     * <p>If either of the get/is method alternatives is found on the class, but an appropriate
     * <code>setName()</code> method is not found, the <code>Property</code> will be
     * Calling the method on such property is allowed, but will have no effect.</p>
     *
     * @param hostType hostType
     * @param valueType valueType
     * @param name name
     * @param <T> T
     * @param <V> V
     * @return Property
     */
    public static <T, V> Property<T, V> of(Class<T> hostType, Class<V> valueType, String name) {
        return new ReflectiveProperty<T, V>(hostType, valueType, name);
    }

    /**
     * Sets the value on <code>object</code> which this property represents. If the method is unable to set the value
     * on the target object it will throw an { UnsupportedOperationException} exception.
     *
     * @param object object
     * @param value value
     * @throws UnsupportedOperationException
     */
    public void set(T object, V value) {
        throw new UnsupportedOperationException("Property " + getName() + " is read-only");
    }

    /**
     * Returns the current value that this property represents on the given <code>object</code>.
     *
     * @param object object
     * @return V
     */
    public abstract V get(T object);

    /**
     * Returns the name for this property.
     *
     * @return mName
     */
    public String getName() {
        return mName;
    }

    /**
     * Returns the type for this property.
     *
     * @return mType
     */
    public Class<V> getType() {
        return mType;
    }
}
